This invention is related to 2-oxo-piperazinyl-triazine ("PIP-T" for brevity) compounds in which a polysubstituted piperazinone ("PSP") substituent is linked to the triazine ring through a single N (nitrogen) atom and at least two C (carbon) atoms, hence termed "distally linked". The term "polysubstituted" refers specifically to a piperazinone ring in which at least the N.sup.4 -adjacent C atoms (at the 3 and 5 positions) are each dialkyl-substituted, or one of the 3 or 5 C atoms is shared by a spiro cycloalkylene substituent, and the other is dialkyl-substituted.
More particularly, this invention is related to PIP-T compounds in which the PSP is connected to the triazine ring with a branched bridge, so termed because the bridge includes at least three serially linked atoms, the first, a N atom bound to the triazine ring, then two C atoms, and the N-adjacent C atom is always disubstituted.
PIP-T compounds including bis compounds and oligomers thereof having a polymethylene bridge (unbranched) are disclosed in our U.S. Pat. No. 4,480,092 ("the '092 patent") for use as ultraviolet ("UV") light stabilizers in organic materials, whether natural or synthetic, which are to be protected against degradation by UV light by incorporating a UV light stabilizer in the material.
Many classes of compounds are known to be useful UV light stabilizers, some being more effective than others. Particularly effective 2-keto-diazacycloalkanes which provide stabilized compositions resistant to degradation by UV light, include the 2-keto-1,4-diazacycloalkanes disclosed in U.S. Pat. No. 4,190,571; and, the 2-keto-1,5-diazacycloalkanes disclosed in U.S. Pat. No. 4,207,228. Other 2-keto-diazacycloalkanes useful as UV light stabilizers are disclosed in U.S. Pat. Nos. 3,919,234; 3,920,659; and 3,928,330 which teach substituted piperazinediones. Cycloalkanes useful as UV light stabilizers are disclosed in Ger. Offen. No. 2,315,042; Japanese Pat. Nos. 7,453,571 and 7,453,572.
The compounds of this invention belong to a well-recognized chemical class of UV light stabilizers known as multi-ringed triazine derivatives. Though most such derivatives disclosed as UV light stabilizers have a significant level of UV-stabilization ("UV-S") activity, each has one or more serious drawbacks which makes the one less desirable from a practical, utilitarian point of view, than another having a less serious drawback. This reality dictates the unending search, even in the narrow field of multi-ringed triazine derivatives, for compounds with better UV-S activity, and results in discarding numerous multi-ringed triazine derivatives which have no appreciable UV-S activity, if at all.
Prior art multi-ringed triazine derivatives with UV-S activity are also disclosed in U.S. Pat. Nos. 4,086,204; 4,051,137; 4,108,829; French Pat. No. 2181 059; and, Japanese Pat. No. 51-4247; inter alia.
In particular regard to our '092 patent, we found that a distally linked PSP was unexpectedly effective not only for its UV-S activity, but also for its antioxidant ("AO") activity, particularly in combination with certain hindered phenols, as disclosed in our copending patent application Ser. No. 721,270 filed Apr. 9, 1985.
We disclosed in our '092 patent how to provide a bridge of plural atoms for the critical distally linked rings. We started with a particular class of alkylated polyalkylenepolyamine ("PAPA"), namely a N-(alkyl)-N'-(aminoalkyl/aryl/aralkyl/cycloalkyl)-1,p-alkanediamine, wherein "p" is the number of methylene C atoms (hereafter "2AAD" for brevity), and one primary amine group was free, the other was substituted and hindered. The process comprises reductively alkylating a particular class of PAPA, such as a N'-(aminoalkyl/aryl/aralkyl/cycloalkyl)-1,p-alkanediamine (hereafter "2AD" for brevity) with a ketone in the presence of a Group VIII metal hydrogenation catalyst and a solvent for the reactants, by carrying out the reaction under elevated temperature and pressure to produce the 2AAD compound; separating the solvent from the reaction mass; adding chloroform and a ketone, preferably in the presence of a phase transfer catalyst; and, carrying out the reaction to produce a PSP which is recovered. The PSP is then reacted with cyanuric chloride or other reactive triazine compound. In a particular preferred embodiment of the invention, a PSP is produced from 2AD using a ketone as a reactant to produce 2AAD; and then, again using a ketone as a reactant, to cyclize the 2AAD. The PSP is then coupled with a triazine ring-containing compound to provide at least one distally linked PSP substituent on the triazine ring.
The phase transfer catalyzed reaction referred to hereinabove is known as the "ketoform reaction" disclosed in greater detail in U.S. Pat. No. 4,167,512, also in an article titled "Hindered Amines. Novel Synthesis of 1,3,3,5,5-Pentasubstituted 2-Piperazinones" by John T. Lai in J. Org. Chem. 45, 754 (1980), and in our '092 patent, relevant parts of all of which are incorporated by reference thereto as if fully set forth herein.
The ketoform reaction may also be carried out without a phase transfer catalyst as disclosed in U.S. Pat. No. 4,466,915 which is incorporated by reference thereto as if fully set forth herein.
The "2AAD" compound, for example, N-(2-butyl)-N'-(2-amino-2-methylpropyl)-1,2-ethanediamine (identified as 1A herebelow), provided a hindered primary amine group by introducing a substituent at the N-position, which is precisely where it was needed to allow us to use the subsequent ketoform reaction to close the ring and form the PSP by connecting the unhindered primary amine group and the intermediate secondary amine group. It was this blocking of the N-position which so effectively allowed cyclization of the unhindered primary amine group and the next adjacent secondary amine group with such regioselective specificity, as was noted in the Lai article, supra.
Thus, it became evident, and it was our belief at that time, that the desired reaction required that one unhindered primary amine group only be left on a 2AAD if it was to be cyclized effectively. It was obvious that if two unhindered primary amine groups were present on a 2AAD, each would be equivalent to, and as active as, the other, and, in a ketoform reaction, both would react with the chloroform generating a trichloromethide ion, in turn resulting in an array of unwanted compounds, few, if any, of which would be cyclized so as to have formed the piperazinone ring.
This invention documents the error of that belief. We accidentally found that the desired reaction proceeded with unhindered or "free" terminal primary amine groups. In other words, blocking the N-position, by converting the primary amine group to a secondary amine group, could be avoided if we disubstituted the C atom adjacent the N-position, thus making both terminal primary amine groups equivalent and equally unhindered. After the ketoform reaction, after the PSP is formed, we are left with a terminal free primary amine group--a fortuitous discovery which leaves the free primary amine to react directly with a reactive triazine compound. From an economic point of view, this is highly fortunate.
Typically, PIP-T compounds are used as photostabilizers ("PS") in conjunction with a hindered phenol antioxidant ("AO") This appears to be a peculiarity of PIP-T compounds since it has been found that there is generally a strong antagonistic effect between many a hindered amine light stabilizer ("HALS") and a hindered phenol AO used in combination for the stabilization of polymers (see "Photostabilizing Performance of a Hindered Piperidine Compound in Polypropylene Film: Antioxidant/Light Stabilizer Effects" by N. S. Allen Polym. Degrad. Stabil. 2, 129 (1980) and "Catalytic Thermal Oxidation of Phenolic Antioxidants by Hindered Piperidine Compounds" by N. S. Allen Polym. Degrad. Stabil., 3, 73 (1980-81).
It was also known that a particular hindered phenol AO, namely tris(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate* commercially available as Good-rite.RTM.3114, and a bis(hindered piperidine) PS commercially available as Tinuvin.RTM.770, showed an unexpectedly beneficial coaction, as disclosed in "Interaction Between Antioxidants and Hindered Piperidine Compounds in the Photostabilization of Polypropylene: Influence of Processing History" by N. S. Allen et al, Polym. Photochem. 1, 11 (1981). FNT *also named 1,3,5-tris[3,5-di-t-butyl-4-hydroxyphenyl)-methyl]-1,3,5-triazine-2,4,6-(1 H,3H,5H)-trione
It was further known that bis-1-(piperazin-2-one) provided not only excellent photostabilization properties as disclosed in U.S. Pat. No. 4,190,571 but also excellent AO properties, as disclosed in U.S. Pat. No. 4,309,336. Moreover, the bis-1-(piperazin-2-one), like many other hindered piperazin-2-one PS compounds, in combination with hindered phenol AOs, were more effective as both PSs and AOs than the sum of their individual effectiveness as PSs and AOs, as disclosed in "Hindered Diazacycloalkanones as UV Stabilizers and Antioxidants" by J. T. Lai et al Polym. Preprints, 25(1), 1984.
Yet, quite surprising is the disclosure that commercially available Chimassorb 944 when used in combination with BHT, Good-rite 3114 and Irganox 1010 is indeed less effective as determined by Weather-O-Meter tests (see brochure entitled "Light Stabilization of Polypropylene Multifilaments and Monofilaments" published by Chimosa S.P.A. (1978), FIG. 3.
From the foregoing unpredictable behavior of particular HALS in combination with hindered phenol AOs generally, it is evident that the effectiveness of any HALS which is structurally dissimilar from the foregoing HALS, ca be no more predictable. Certainly, there was no reason to expect that a compound from the particular class of HALS containing linked piperazinone and triazine rings, when combined with one of specific hindered phenols, would exhibit a higher degree of PS and AO activity than that obtained by summing the activity of the individual HALS and hindered phenol when used separately. This unique synergistic behavior of a PIP-T compound is now attributable to its being less basic, because of the 2-one group, than compounds containing linked triazine and pyridine, piperidine, or piperazine rings.